Register to reply 
Parallax and distance 
Share this thread: 
#1
Oct913, 06:42 AM

P: 24

A star exhibits a parallax of 0.250 arcseconds when measured from Earth.
a) What is its distance (pc)? I know this uses the formula d=1/p, so i can solve this very easily b) What would its parallax be if measured from Venus’s orbit (arcseconds)? (Look up the one parameter you need to solve this using the relevant equation.) I don't know what to do here at all though, I can't look up it's distance from Venus because its an arbitrary star...so what do i do? Can someone guide me to the right direction?? Thanks 


#2
Oct913, 07:15 AM

P: 702

What is the base of the triangle used to measured parallax of distant stars?
(by the way, you should post these kind of questions in the homework section) 


#3
Oct913, 07:24 AM

Math
Emeritus
Sci Advisor
Thanks
PF Gold
P: 39,491

Do you know what parallax means? Imagine lines drawn from this "arbitrary star" to opposite ends of Venus' orbit (on the line through the sun perpendicular to the line to the star). That gives you an isosceles triangle with one angle (the one at the star) known and one side (the distance across Venus' orbit). You can use the "cosine law" to find the lengths of the two other sides (the distance from Venus to the star).
"I know this uses the formula d=1/p". There's your problem you know formulas but you don't know the reasoning behind the formulas so you don't know how to change them when the situation changes! 


Register to reply 
Related Discussions  
Measuring the distance to stars using parallax  Astronomy & Astrophysics  3  
Measuring distance with parallax  Introductory Physics Homework  10  
Parallax & distance  Introductory Physics Homework  2  
Measuring the distance to Mars with parallax.  Introductory Physics Homework  0  
Distance = 1/parallax  Introductory Physics Homework  2 